Fix for bug reported by Evzen Muller on llvm-commits: make sure to correctly
check the range of the constant when optimizing a comparison between a
constant and a sign_extend_inreg node.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@109854 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
index 12185a3..908a9d8 100644
--- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -1968,12 +1968,9 @@
EVT ExtDstTy = N0.getValueType();
unsigned ExtDstTyBits = ExtDstTy.getSizeInBits();
- // If the extended part has any inconsistent bits, it cannot ever
- // compare equal. In other words, they have to be all ones or all
- // zeros.
- APInt ExtBits =
- APInt::getHighBitsSet(ExtDstTyBits, ExtDstTyBits - ExtSrcTyBits);
- if ((C1 & ExtBits) != 0 && (C1 & ExtBits) != ExtBits)
+ // If the constant doesn't fit into the number of bits for the source of
+ // the sign extension, it is impossible for both sides to be equal.
+ if (C1.getMinSignedBits() > ExtSrcTyBits)
return DAG.getConstant(Cond == ISD::SETNE, VT);
SDValue ZextOp;